Bulmer’s fruit bat (Aproteles bulmerae) is a Critically Endangered megabat known from a single cave in Papua New Guinea’s Hindenburg Range. It is the only member of its genus, feeds mainly on figs and other fruit, and is one of the largest cave-roosting bats in the world — yet fewer than 160 individuals have ever been confirmed, making it possibly the rarest bat on Earth. It is placed on the list of endangered species.
- Status: Critically endangered
- Known as: Bulmer’s Fruit Bat, Bulmer’s flying fox (Aproteles bulmerae).
- Estimated numbers left in the wild: Fewer than 160 (last confirmed count, 1993) — no dedicated survey has verified this figure since.
What is the Bulmer’s Fruit Bat?
Only one Bulmer’s fruit bat has ever been formally examined by scientists — an adult female that weighed roughly 600 grams (1.3 lb), among the heaviest of all fruit bats. The species was first described in 1977 from roughly 12,000-year-old sub-fossil bones found in Papua New Guinea’s central highlands, and its genus, Aproteles, is monotypic — Bulmer’s fruit bat is the only species in it, and the only surviving member of a lineage otherwise known only from the Late Pleistocene fossil record.
One of its most unique features is that it has no fur on its back – each wing membrane extends up over its shoulder to the spine, where the membranes meet. These bats have a 1-meter wingspan and range from an umber color to completely black. They smell intensely of musk.
Fascinatingly, Bulmer’s fruit bat is among the world’s most maneuverable bats, able to hover in place like a hummingbird or even fly in reverse. It is perhaps this airborne agility that allows it to roost in caves despite its large size — it is one of the world’s largest cave-roosting bats.
The bat species often known as mountain bats live in rocky areas with medium-height forests and chilly temperatures, which offer the sorts of fruit they like, such as figs.
They emerge only after it is completely dark, and they are prepared to fly 30 or 40 kilometers to their food sources, returning to their roost before sunrise.
These bats are known to be a cave dweller and there is only a single cave in Papua New Guinea there they are known to be found.
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Behavior
The fruit bats of the Bulmer family are unusual in that they demonstrate intriguingly cooperative behavior, such as avoiding humans. When it’s time to fly to the feeding grounds, several scouts emerge from the cave and criss-cross the area around the entrance, seeking for human presence.
They give a steady series of birdlike calls while scouting, apparently to inform the bats in the cave of the situation. If there are humans, the bats will remain in their cave for hours, waiting for the intruders to depart. Despite these bird-like warning calls, Bulmer’s fruit bat is a true bat — a megabat in the flying fox family (Pteropodidae), not related to birds.
Another interesting adaptational characteristic of bulmer’s fruit bat is its ability to fly backwards.
This unique ability could be explained by evolutionary pressure for this species to evade bird predators that can attack from behind, however little research has been published about the bulmer’s fruit bat’s ability to fly backwards.
This has piqued the public’s interest in bulmer’s fruit bats, their predators, and where they dwell even more. Knowing where bats live is critical since it might help us understand the dangers these creatures face.
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Breeding
Females first become pregnant at three years of age and carry their babies with them to the feeding grounds for several weeks until the young bats become too large and heavy to carry.
They only known roost of this species is an enormous vertically positioned cave located near a 2,400-meter escarpment. Its surroundings are thick with mossy montane firs and pines.
Lifespan of a Fruit Bat
The bulmer’s fruit bat lives approximately 15-18 years in the wild, but can live much longer in captivity.
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Location
Bulmer’s fruit bat is found only in Papua New Guinea. These bats live in mountainous terrain, and the only confirmed living colony is in a single cave known locally as Luplupwintem, in the Hindenburg Range of Western Province, Papua New Guinea.
There may also be populations in the island’s isolated mountain regions.
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Conservation
Bulmer’s fruit bat is possibly the rarest bat on Earth, and is most vulnerable to hunting for food and the loss of the fruit trees it depends on.
Because its entire known population lives in one cave, a single hunting event, disease outbreak, or cave disturbance could wipe out the species — which is exactly what nearly happened in the 1970s (see Threats, below).
Threats
When anthropologist David Hyndman first visited Luplupwintem cave in 1975, local hunters described the colony as abundant, numbering in the thousands. But a sudden inflow of outside cash into the region in the mid-1970s let villagers buy ropes, caving gear, and shotguns — and hunters supplying meat for food blasted large numbers of bats off the cave walls.
When Hyndman returned to the cave in 1977, it was almost empty — only two bats flew out. Because the species is known from just this one colony, that single hunting event alone came close to causing its extinction, and any renewed hunting pressure today poses the same existential risk.
Destruction of fruit trees in the area is another menace to the bats’ survival.
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Conservation efforts
There is no dedicated conservation program for Bulmer’s fruit bat today. Historically, the Luplupwintem cave colony was protected informally by local taboos observed by the Wopkaimin people, but that protection broke down once outside cash made hunting equipment accessible.
With no active monitoring or protection in place, the species remains completely vulnerable and could be wiped out at any time. Its IUCN Red List status is Critically Endangered.
The future of the Bulmer’s fruit bat colony
Unlike many endangered species, the cause of Bulmer’s fruit bat’s collapse is well documented: hunting pressure that followed the arrival of a local cash economy in the mid-1970s, not habitat loss or climate change. That means the outcome is, in principle, within human control — if the Luplupwintem cave colony is protected from hunting, it can recover.
Because the species is so hard to survey in its remote cave habitat, some biologists hold out hope that undiscovered colonies survive elsewhere in Papua New Guinea’s highlands, where the fossil record shows Bulmer’s fruit bat once ranged more widely. But with no dedicated conservation program in place, its future remains highly uncertain.
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Organizations
There are several environmental organizations that assist large fruit bats globally, such as WWF. They also work to save other species, such as tigers, snow leopards, and other fruit bats.
WWF strives to educate the public about the necessity of conservation for all species on Earth. Their aim is to stop habitat devastation so that wildlife may thrive in their natural habitats.
Do you know of or are you a part of an organization that works to conserve the Bulmer’s Fruit Bat?
Then please contact us to have it featured on Our Endangered World.
Frequently Asked Questions (FAQs)
What is bulmer’s fruit bat?
Bulmer’s fruit bat (Aproteles bulmerae) is a Critically Endangered megabat that lives in a single cave in the highlands of Papua New Guinea. It is one of the world’s largest cave-roosting bats, feeds predominantly on figs, and is threatened mainly by hunting for food and the destruction of the fruit trees it depends on.
How did bulmers’ fruit bats become endangered?
Bulmer’s fruit bats are threatened by hunting for food, destruction of fruit trees and deforestation.
The species is endemic to Papua New Guinea — it did not originate elsewhere and was never introduced. Its only known colony was hunted to near-extinction in the 1970s after locals gained access to guns and caving equipment.
Why is the bulmer’s fruit bat endangered?
The bulmer’s fruit bat is Critically Endangered mainly because of hunting and the loss of the fruit trees it depends on. Its entire known population lives in a single cave, so any localized threat could wipe out the species.
What are bulmer’s fruit bats threatened by?
Little is documented about natural predators of Bulmer’s fruit bat. Its biggest threat by far is humans: hunting for food and destruction of the fruit trees it relies on, made worse by the fact its entire known population lives in one cave.
Why are bulmer’s fruit bats not being conserved yet?
It’s difficult to conserve Bulmer’s fruit bat because its only known colony lives deep in a remote mountain cave in Papua New Guinea, making it hard to monitor or protect. No dedicated conservation program currently exists, and the bats remain threatened by hunting for food and the loss of the fruit trees they depend on.
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